Treatment of cellulosic textiles with 1 - substituted - 3,5 - dimethylol-2,6-dihydrotriazin-4-one



United States Patent ABSTRACT OF THE DISCLOSURE Crease-resistance is imparted to cellulose textiles by (1) impregnating them with an aqueous bath containing (a) a triazin-4-one and (b) sufiicient mineral acid to give a pH of 2-3.5; (2) drying and curing the impregnated fabric at 200-300" F. to a moisture content of 1-20 percent; and (3) removing residual acid.

This invention relates to novel methods of treating textiles and, more particularly, it is directed to the treatment of textiles for imparting crease-resistance thereto.

Nitrogen-containing compounds have been extensively used in the treatment of textiles for the purpose of impairing crease-resistance. Such nitrogen-containing compounds include l-substituted 3,5 dimethylol 2,6 dihydrotriazine-4-ones and alkaylated, e.g. methylated, derivatives thereof. As an illustration, United States Pat. 3,004,870 teaches a process for creaseproofing cellulose fabric by application of the substituted triazin-4-one in the presence of a relatively mild catalyst and effecting the reaction between the triazin-4-one and the cellulose by curing at relatively high temperatures. According to that manner of treating the fabric, only low to moderate levels of wrinkle resistance and wash/ wear properties are obtained because excessive losses in tensile strength and/or abrasion resistance would occur if higher concentrations of resins were used or if the curing time and/or temperature were increased. In addition, by that method of curing the resin through the use of relatively high temperatures and mild catalysts, the reaction or curing occurs with the fabric in bone-dry condition and with the cellulose fiber of the fabric in a collapsed condition. Under those conditions the fabric develops a low to moderate degree of wrinkle resistance when dry, but the wet wrinkle resistance in inadequate to provide good smooth-drying properties when the fabric is laundered and then hung to dry.

It is known to crosslink cellulose While it is in the wet state. Also, mineral acids have been used as catalyst in crosslinking cellulose with nitrogen-containing compounds. For example, in British Pat. 905,044 it is taught to apply a methylolated nitrogen-containing compound in the presence of a mineral acid; thereafter to hold the saturated fabric for a period of time to allow the compound to react with the cellulose; and then to wash out the acid before attempting to dry the treated cloth.

Similarly, French Pat. 1,275,086 teaches the application of formaldehyde and/or a variety of aminoplast compounds in the presence of hydrochloric acid. Then the impregnated fabric is held for 1 to 60 minutes at essentially room temperature under such conditions that the fabric does not dry substantially. After this holding period, the fabric is thoroughly rinsed before drying is attempted.

In South African Pat. 62/545 it is taught that cellulose textiles may be treated with a l-substituted 3,5 dimethyl-2,6-dihydrotriazini-one with an acid catalyst. The impregnated material then should be held in a smooth and crease-free condition for an extended period (at least 2 hours) before attempting to further process the fabric. Thereafter the fabric is washed free of reactant and catalyst and dried.

In United States Pat. 3,046,079 it is taught that cotton may be steeped in a solution containing mineral acid plus an aldehyde for a period of time at a temperature not to exceed 45 C. so as to permit the reaction to reach the desired stage. The reaction is stopped at the desired stage by washing the fabric free of aldehyde and acid or by neutralizing it with a base. Then the fabric is dried.

In all of the above-mentioned patents the desired reaction of curing is substantially completed while the fabric is maintained in the wet state, e.g., by steeping it in an aqueous bath of the catalyst and crosslinking agent or by wrapping the impregnated fabric in an impervious wrapping scch as polyethylene. Drying of the fabric is discouraged during this stage so an to minimize non-uniform crosslinking. After the desired degree of reaction or curing has taken place, the acid catalyst is removed by neutralization or by washing or both. The fabric is then dried.

These prior art procedures are disadvantageous from a practical standpoint in that time, equipment, and space munt be provided for maintaining the impregnated fabric in the wet state while curing takes place. This is further complicated by the requirement that the fabric be kept in a smooth, crease-free condition and in the final desired shape while curing takes place, which can be quite diificult to do while maintaining the fabric in a uniformity wet condition.

It is therefore an object of this inevntion to provide a process for imparting a high level of dry and wet crease-resistance to cellulose textiles without causing undue degradation of the fibers of the textile.

Another object is the provision of a process for imparting unexpectedly high levels of crease-resistane to cellulosic textiles without the necessity of maintaining the textile in a wet condition while curing takes place prior to drying.

Another object is the provision of a process for treating textiles to impart unexpectedly high levels of dry and wet crease-resistance and wash/wear properties when the textile is subsequently laundered and dried by any one of the drip drying, spin-line drying or spin-tumble drying procedures.

My invention is based on the unexpected discovery that certain resins can be applied to cellulosic fabrics in the presence of a mineral acid as catalyst without excessive degradation of the fiber while yielding treated fabrics of unusually high wrinkle resistance and wash/wear performance.

By my present invention, I have discovered'that it is possible to use very Strong catalyst to effect a cure without serious damage to the fabric. In particular, I prefer to use mineral acids as the catalyst. When using such strong acid catalysts, I have found that curing of the resin and crosslinking of the cellulose occur while the fabric still has some slight moisture present. Crosslinking occurs before the fiber tends to collapse, thus yielding a fabric which has extremely high levels of both wet and dry wrinkle resistance.

The creaseproofing resins which are best suited for use in my invention are the 1-substituted-3,5-dimethylol- 2,6-dihydrotriazine-4-one or the 3,5-bis (methoxy) derivatives thereof. A general formula of these substituted triazin-4-ones is as follows:

wherein the Rs are H or lower alkyl (3 carbon atoms or less); both Rs may be the same or they may be different; Z is a member selected from the group consisting of alkyl, substituted alkyl, cyclo aliphatic, and aralkyl radicals having not more than carbon atoms. Z may also represent a short aliphatic chain, e.g., an alkylene radical of 1 to 4 carbon atoms, which is di-substituted with triazin-4-one cyclic structures as shown. Although not limited thereto, I prefer to use the simple compounds where the Rs are H and Z is a short aliphatic chain such as methyl, ethyl, chloroethyl, hydroxyethyl, and the like.

As compared to all of the above-mentioned prior art references, my invention possesses extremely important advantages. When using my invention, there is no need to hold the impregnated fabric in the wet state prior to drying for any extended period of time so as to permit the reaction to occur. Instead, through the use of moderately elevated temperatures, I have found that the reaction between the substituted triazin-one and the fabric occurs essentially immediately as the fabric is dried.

For the drying temperature, I prefer to use the range of 200-300 F., preferably approximately 240-260 F. Lower temperatures could be used, but become economically unattractive because it slows down the drying operation. Temperatures above approximately 300 F. should be avoided because of the danger of tendering the cloth.

The time of drying is controlled in large part by the weight of the cloth, the temperature of drying, the amount of air circulation, and other factors. In general, it is preferred to dry the fabric until there is a residual moisture content of 1-20%, preferably 28%. As an example, with a fabric weighing approximately 4 ounces per square yard, it would require approximately 1.53.0 minutes to dry the fabric when using a drying temperature of approximately 250 F.

Following the drying, the fabric should, preferably, be thoroughly rinsed and the acid neutralized with appropriate alkali such as sodium bicarbonate, sodium carbonate, and the like.

The fact that I can dry the fabric practically to dryness at elevated temperatures without damaging the cloth is most surprising and unexpected considering the presence of the mineral acid as catalyst. Although I am not certain of the actual reaction mechanism, it is possible that the substituted triazin-4-one forms a salt with the acid which results in less deterioration of the cellulose than would be the case if the mineral acid were used with other types of crosslinkers such as aldehydes, dimethylol cyclic ethylene urea, bis(methoxy methyl)uron, and the like.

As for the selection of the acid which is useful as a catalyst in this invention, practically all mineral acids are satisfactory, but hydrochloric acid, sulfuric acid, and phosphoric acid are preferred. In general, an adequate amount of mineral acid is used to provide a padding bath with a pH of from approximately 2.0 to approximately 3.5, preferably 2.5 to 3.0.

The amount of triazin-4-one in the impregnating bath is not narrowly critical and, illustratively, can be varied from 1 to 30% based on the weight of said bath. The amount of acid catalyst also is not narrowly critical and, illustratively, can be varied from 0.1 to 20% based on the weight of the bath, but in any event the amount of mineral acid to be used should provide a pH in the above stated range. The amount of impregnating bath applied to the textile likewise is not narrowly critical; for example, wet pick-ups of 40 to on the bath based on the dry weight of the textile can be employed.

Although it is essential to utilize the triazin-4-one compounds (as already described) in the practice of my invention, it is not essential to utilize the triazin-4-one exclusively. Instead the triazin-4-one may be used in admixture with other cellulose crosslinking agents such as dimethylol propylene urea, dimethylol cyclic ethylene urea, bis(methoxy methyl)uron, hexa(methoxy methyl) melamine, methylol ethyl carbamate, formaldehyde, and the like in amounts of about 1 to 20% based on the weight of said bath. Mixtures of one or more triazin-4- one may be used along with mixtures of one or more of such non-triazin-4-one crosslinkers.

In addition to the crosslinking agents themselves plus the mineral acid catalyst, other additives may be included in the treatment such as softeners, lubricants, stiffening agents, water repellents, oil repellents, and the like.

Inasmuch as the crosslinking occurs with cellulose (such as cotton, regenerated cellulose, linen), the invention is applicable to cellulosic fabrics. However, extremely useful results are obtained when cellulose comprises only a portion of the fiber content of a fabric. Thus, the invention includes treating cotton fabric, fabrics made from rayon, linen fabrics, blends of cotton with rayon, blends of cotton with hydrophobic fibers, such as polyester, nylon, and acrylic fiber as well as blends of rayon with such hydrophobic fibers. The only criterion as to synthetic fiber composition is to be sure that the synthetic fiber is not damaged or destroyed by the mineral acid catalyst used. Blends containing as little as 20% cellulose are found useful in the practice of the invention.

The following examples are given. All parts indicate percentage by weight. Wrinkle recovery was measured by the AATCC Test Method, 66l959T. Tensile strength 'was measured by Fed. Spec. CCCT-19lb, Method 5100'. Flex abrasion was measured by Fed. Spec. CCC-T-19lb, Method 5300. Wash/Wear ratings were determined by AATCC Test Method 88A-l964T.

Example 1 An aqueous padding bath was prepared to contain 12% 1-ethyl-3,5-dimethylol-2,6-dihydrotriazin-4-one, 1.6% of concentrated hydrochloric acid, and 3% of a polyethylene softener. The pH of this padding bath was 3.0. A swatch of cotton broadcloth was padded through this solution and then was dried for 3 minutes at 250 F. to a moisture content of 3 to 5 weight percent. The dried fabric was then rinsed in detergent and soda ash solution and then with several rinses of plain water. Following this, the fabric was dried and then tested for various properties. The treated fabric was found to have a total dry wrinkle recovery (warp and fill) of 318 and a wet Wrinkle recovery of 310; tensile strength of 26 pounds in the filling, and a flex abrasion of 344 cycles in the warp before failure.

When the same resin is applied with maleic acid catalyst and cured in accordance with conventional curing procedure as taught in U.S. Pat. 3,004,870, the treated fabric has a total dry wrinkle recovery of only approximately 280, but will show even lower tensile strength and flex abrasion results.

Example 2 An aqueous padding bath is prepared to contain 10% of dimethylol 1,3-propylene urea plus 12% of the same triazone used in Example 1. In addition, 3% of concentrated hydrochloric acid is added plus 2% of a polyethylene softener. The resulting padding bath has a pH of 2.4. An all-cotton broadcloth Weighing approximately four ounces per square yard was padded through the above solution and was dried 2 minutes at 250 F. to a moisture content of 7 to 10 weight percent. Thereafter, the fabric was after-treated by thorough soaping off with detergent and soda ash solution and plain water rinsing. After drying the fabric and conditioning, the cloth was found to have a total dry wrinkle recovery of 317 and a tensile strength in the filling direction of 30 pounds. After launderings, the wash/wear properties were checked. The fabric had a wash/ wear rating of 4.4 when the fabric was spin-line dried and a wash/wear rating of 4.8 when the fabric was spin-tumble dried. The initial treated fabric had a flex abrasion of over 500 cycles when tested by the Stoll Flex tester in the warp direction.

Example 3 An aqueous padding bath was prepared to contain 18% of 1 hydroxy ethyl 3,5-dimethylol-2,6-dihydrotriaZin-4- one plus 3% of concentrated hydrochloric acid and 3% of an acrylic latex. A poplin fabric comprising an intimate blend of approximately 65% polyester fiber plus 35% cotton and weighing approximately 4.5 ounces per square yard was padded through this solution to provide a wet pick-up of approximately 50%, and then it was dried for 1 minute at 275 F. to a moisture content of 5 to Weight percent. Following this, the fabric was thoroughly soaped off with detergent and soda ash solution and then was rinsed with plain water and finally dried. The fabric showed excellent wet and dry wrinkle recovery as well as excellent wash/wear properties when laundered and dried by either drip drying, spin-line drying, or spin-tumble drying. Abrasion resistance was also excellent, being approximately the same as the untreated fabric.

Example 4 An aqueous padding bath was prepared so as to contain 24% of the same triazone as in Example 1, and in addition it contained 4% of concentrated hydrochloric acid plus 3% of a typical cationic softener. A twill fabric comprising a blend of 50% cotton plus 50% of high wet modulus rayon and weighing approximately 6 ounces per square yard was padded through the above solution. The Wet pick-up was approximately 70%, and the fabric was dried for 4 minutes at 240 F. to a moisture content of 10 to weight percent. After soaping off and rinsing, the fabric was dried. Following this, the fabric was impregnated with a solution containing 6% of magnesium chloride, and then it was dried again. This fabric was then made into a pair of mens trousers, and, after sewing, the trousers were pressed on a high pressure, high temperature press for seconds at 400 F. The resulting garment had excellent permanent press properties, showing a high level of wrinkle resistance and smooth drying properties after laundering. The tensile strength, the tear strength, and the abrasion resistance were sufficiently high so as to provide a serviceable garment.

This example illustrates a variation of my invention wherein the crosslinks may be reformed during pressing and/or subsequent curing of completed garments. Although the example illustrates the use of a second catalyst (magnesium chloride), the use of a second catalyst is not always required but will depend on the specific agents used, the fiber composition of the fabric, and the end use of the garment being manufactured.

Example 5 An aqueous padding bath is prepared with 12% of the same triazone as used in Example 3. In addition, 3.6% of 96% aqueous sulfuric acid plus 3% of a polyethylene softener are added. An 80 x 80 count cotton print cloth is impregnated through the above solution followed by drying for 90 seconds at 210 F. to a moisture content of 15 to 20 weight percent. Following this, the fabric was soaped off, rinsed, and dried. It was found to have excellent wet wrinkle recovery, dry wrinkle recovery, and unusually high. tensile and tear strength as well as abrasion resistance, considering the high level of wrinkle resistance obtained.

Example 6 Example 5 was repeated except that the padding bath contained 10% of phosphoric acid strength). The pH of the padding bath was 2.8. The treated fabric gave equally good results.

What is claimed is:

1. A process of treating cellulosic textiles to impart wet and dry crease-resistance thereto comprising impregnating a cellulosic textile with an aqueous bath containing sufiicient mineral acid to provide a pH of about 2.0 to about 3.5; about 1 to 30 weight percent of a triazin-4- one having the formula wherein n is an integer of l to 2, the R groups are members of the class consisting of hydrogen and alkyl radicals having not more than 3 carbon atoms and may be the same or different in each molecule, and Z is a member selected from the class consisting of alkyl, hydroxy-substituted alkyl, chlorine-substituted alkyl, cycloalkyl, and aralkyl radicals having not more than 10 carbon atoms when n is one and an alkylene radical of 1 to 4 carbon atoms when n is two; and about 1 to 20 weight percent of N,N-dimethylol-1,3-propylene urea; forthwith drying the resulting impregnated textile at a temperature of about 200 to about 300 F. until the moisture content of said fabric is about 1 to about 20 percent based on the dry weight of said textile; and thereafter removing residual acid from said textile.

2. Process as claimed in claim 1 wherein said catalyst is hydrochloric acid.

3. Process as claimed in claim 1 wherein said catalyst is sulfuric acid.

4. Process as claimed in claim 1 wherein said catalyst is phosphoric acid.

5. Process as claimed in claim 1 wherein said triazin- 4-one is 1-ethyl-3,5-dimethylol-2,6-dihydrotriazin-4-one.

6. Process as claimed in claim 1 wherein said triazin- 4-one is 1-hydroxyethyl-3,S-dimethylol 2,6 dihydrotriazin-4-one.

7. Process as claimed in claim 1 wherein said residual acid is removed by neutralization.

8. Process as claimed in claim 1 wherein said textile is composed of cotton.

9. Cellulosic textile treated by the process claimed in claim 1.

OTHER REFERENCES Marsh: Crease Resisting Fabrics, Reinhold, pp. 112- 115 (1962).

JOHN DAVID WELSH, Primary Examiner US. Cl. X.R.

8ll6.3; 1l7-139.4 

